NEW YORK — The Boy Scouts of America on Friday proposed to lift a ban on gay Scouts but to continue prohibiting gay adults from participating in the hundred-year-old American institution.

Key donors and supporters, including the Church of Jesus Christ of Latter-day Saints — the Mormons — and AT&T did not immediately take a position on the proposal, while gay rights groups said continuing to bar gay adults was unacceptable, though they welcomed the change for youths.

Scout leaders in May will vote on the proposal, which would be a sweeping change for an institution that in 2000 won a Supreme Court battle over its right to exclude gays.

The Boy Scouts’ decision is one of the focal points of a broad gay rights debate in the United States. In the coming months, the Supreme Court will rule on whether to strike down parts of a federal law that defines marriage as the union between a man and a woman, and in 2011, the military repealed a ban on gays serving openly.

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Public opinion polls show rising support for gay rights, but there is still a strong social conservative movement opposing acceptance of gays in institutions such as marriage.

The Boy Scouts proposal reflects the complexity of compromises — it would create a situation where a gay youth could become a Scout and then be forced to resign when he becomes an adult.

If the resolution is approved, “no youth may be denied membership in the Boy Scouts of America on the basis of sexual orientation or preference alone,” Deron Smith, the organization’s spokesman, told Reuters.

But the policy is not changed for adults, the group said, and an internal document obtained by Reuters says that when youth members become adults, then they “must meet the requirements of our adult standards” to remain in the group.

The new resolution is the result of a study Boy Scouts of America spokesman Smith called “the most comprehensive listening exercise in the history of Scouting,” which found parents in three of four U.S. regions opposed the current membership policy.

The report found religious groups linked to the Scouts were concerned with homosexual adult leaders, not with youth, and concluded “a change in the membership policy specific to youth only would be consistent with the religious beliefs of the BSA’s major chartered organizations.”

Gay rights groups were quick to say the decision was not far-reaching enough.

“By refusing to consider an end to its ban on gay and lesbian parents, the Boy Scouts have missed an opportunity to exercise leadership and usher the organization back to relevancy,” said Rich Ferraro, a spokesperson for GLAAD, which promotes lesbian, gay, bisexual and transgender rights.

Mormon church spokesman Michael Purdy said church leaders “will take the time needed to fully review the language and study the implications of this new proposal.” An AT&T official did not have a comment.

Some faith-based groups had opposed admitting gays on religious grounds, while Boy Scouts of America board members including Jim Turley, chairman and chief executive of Ernst & Young, and AT&T Inc. CEO Randall Stephenson have publicly supported a change.

“This was an exceptionally difficult decision as a business,” said Patrick Boyle, whose 1994 book “Scout’s Honor” examined sexual abuse in the Boy Scouts of America. “They were stuck in a very bad spot with their constituents divided — constituents being the parents, and also the churches and the businesses that support the Scouts.”

The road to resolution has been a long one. In July 2012, the group’s board voted to uphold the gay ban. Six months later, group leaders said they were mulling over whether to remove the national restriction, leaving local branches to decide whether to admit gays and lesbians on their own. A final vote, expected in February, was delayed after a request from a coalition of 33 faith-based councils that represent about one-fifth of all youth members in the Boy Scouts.

Boyle notes that this reversal “shows how the gay rights movement has caught fire in the past dozen years.”

“It wasn’t very long ago that these guys stood before the Supreme Court and said that denying gays membership was a fundamental cornerstone belief of their organization,” Boyle said, citing a 2000 Supreme Court ruling that granted the Boy Scouts the right to uphold their membership policy.

Chuck Small, a Boy Scouts adult leader and the parent of 10- and 12-year-old Scouts in South Carolina, welcomed the latest change.

“It’s a hard and divisive issue, but what it comes down to is that we learn more from people who are different from us than people who are like us,” Small said.

“I think it’s a healthy thing, and I hope my boys are up to the challenge to accept people for what they do, rather than what they believe or how they’re made up.”